FLAT vs DOMED washers for tub/sink

[Conase]

I recently replaced the rubber washers on an old shower valve with HOT+COLD+DIVERTER setup.

I also had to replace the seat since it had chewed up one washer.

The rubber washers on the unit were FLAT BLACK RUBBER - 3/8L.

I used DOME SHAPED black rubber washers.

They fit and work fine.

I don't see any difference in operation.

Anyone know any reasons why they - FLAT + DOMED - can't be used interchangeably ?????

I have always used whatever worked.

TIA

[Speedy Jim]

Beveled washers aren't always suitable (depending on seat design) but they usually require less force to seal completely.

Jim

[Conase]

Any wisdom on what to look for in SEAT DESIGN. TIA

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[Speedy Jim]

Older seats with large diam were often cut with flat surfaces; use flat washer for sure. Newer, smaller ones may have a visible chamfer or bevel face. Jim